A Study of Estimation for Steel Bridge Piers considering torsion effects

本研究的目的是估计钢桥墩承受面外循环荷载。为此，考虑扭转效应，对倒L形钢桥墩进行了快速弹塑性分析，并通过倒L形钢桥墩的抗震性能试验验证了数值计算结果。最后，开发了钢桥墩在面外循环荷载作用下的强度和变形能力的试验函数。研究结果表明：随着偏心距的增大，柱的承载力大大降低;柱的屈曲模态分析表明，柱的滞回性能主要受面外弯矩的影响，偏心侧的向内变形主要受循环扭矩的影响;建立了倒L形钢桥墩抗震性能试验系统;研究了偏心率e/r分别为0、2和3时，对柱的弹塑性性能、极限承载力和延性的影响。分析结果表明，在竖向偏心荷载和循环荷载作用下，倒L形钢桥墩的面内变形较大，且对于倒L形钢桥墩而言，竖向偏心荷载和循环荷载作用下的面内变形较大，而对于倒L形钢桥墩而言，竖向偏心荷载和循环荷载作用下的面内变形较大。对倒L形箱形钢桥墩的强度和延性进行了参数分析，提出了评价倒L形箱形钢桥墩强度和延性的经验公式。

The present study is aimed at an estimation of steel bridge piers subjected to out-of-plane cyclic loading. For this purpose, Elastoplastic analysis was carried out at fast considering torsion effect Next, these numerical results were verified by the seismic performance tests of Inverted L-shaped steel bridge piers. Finally, the experimental functions estimating the strength and deformation capacity for steel bridge piers subjected to out-of-plane cyclic loadings are developed. The following conclusions can be obtained :1) With the increase in eccentric distance, the loading-carrying capacity of the columns is greatly reduced.2) Comparison of the buckling modes indicates that the out-of-plane bending moment dominates the hysteretic behavior of the columns, and the inward deformation on the eccentric side is attributed to the effect of the cyclic twisting moment.3) The seismic performance testing system for inverted L-shaped steel bridge piers was developed.4) The eccentricity ratio e/r is selected as 0, 2 and 3, and its influences on the inelastic behavior, ultimate strength and ductility are investigated. It is found that the Inverted L-shaped steel bridge pier deformaed largly in the in^plane direction although the pier was loaded in the out-of-plane direction.5) From the analytical results, it is realized that the eccentric vertical load and cyclic loading pattern will cause a significant in-plane displacement, and in the case of inverted L-shaped piers, strength deterioration is greater than that of T-shaped piers.6) An extensive parametric analysis is performed to propose empirical formulas in order to evaluate strength and ductility of inverted L-shaped box-section steel bridge piers.